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Info Silica Fiber

Source Wikipedia:

Silica fibers made of sodium silicate (water glass) are used in heat protection (including asbestos substitution) and in packings and compensators. They can be made such that they are substantially free from non-alkali metal compounds.

Sodium silicate fibers may be used for subsequent production of silica fibers, which is better than producing the latter from a melt containing SiO2 or by acid-leaching of glass fibers. The silica fibers are useful for producing wet webs, filter linings and reinforcing material.

They can also be used to produce silicic acid fibers by a dry spinning method. These fibers have properties which make them useful in friction-lining materials.[1]

 

Silica-Based Woven Textile products have been specifically designed for high temperature use.
Silica is available in a variety of product forms: Woven Fabrics, Woven Tapes, Non-woven Blankets, Bulk Fiber, Modules, Braiding Yarns, and other specialty forms such as Sleeving, Rope Gasket, and Cord.

Silica textiles provide excellent thermal and acoustic protection. These high-temperature resistant textiles products insulate and provide continuous protection in environments up to 1800°F (982°C), while maintaining their strength and flexibility.

  • Some woven Fabric contain a special coating that provides exceptional functioning when higher temperature performance, up to 2300°F (1260°C), is required
  • Non-woven Felts are available in a specially processed version that provides higher resistance to residual shrinkage (<1%) and degradation in extreme environments.
  • Siilica products can withstand excursions to 2900°F (1593°C) with minimal embrittlement and shrinkage.
  • Silica products are available in > 96% silica content. They resist oxidation, most corrosive solutions and chemicals, and they present no known health hazard.
  • Applications for Silica products range from welding blankets to satellite shrouds, firewalls to aircraft insulation, furnace curtains to thermal couple insulation wrap.
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Silica – Nonwovens

Product Description: 

Silica Needlemats are made from special glass fibers with a filament diameter of 6-9 microns. They represent a modern product generation that, in any aspect, meets with all stringent requirements as to temperature consistency and environmental health standards. Silica glass fibers consist of nearly 95% SiO(2). Because of their low thermal conductivity they are the ideal raw material for the production of flexible insulation mats formed mechanically without the use of chemical bonding agents. These mats keep a very high chemical and physical stability up to 1,800 degr. F. (For application temperatures not higher than 1,200 degrees F, we recommend the more cost efficient E-Glass Needlemat).

The easy handling of the mats allow the cutting of the material into any desired shape and form.

Please click on image to enlarge

SilicaMatThermoConductivitySilicaMat

 Applications: 

  • Industrial ovens
  • Chimneys
  • Kiln furnaces
  • Boilers
  • Steel Industry
  • Gas exhaust systems
  • Laboratories
  • Fire protection

 

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Silica – Fabrics

Product Description:

Silica fabrics are consisting of special glass fibers with an average filament diameter of approx. 6 micron. They represent a modern product generation that, in any aspect meets with all stringent requirements as to temperature consistency and environmental health standards. Approx. 95% of the Silica glass fibers consist of SiO(2). They are the ideal raw material for the production of fabrics and tapes with very high chemical and physical stability of up to 1,800 degr. F. As per customers specification these Silica fabrics can be finished with various coatings.

 Applications: 

  • Fire blankets
  • Welding blankets
  • Removable Insulation covers
  • Insulation pads
  • Industrial and laboratory ovens
  • Household– and boiler industry
  • Heat– and fire protection
  • Steel Industry
  • Automotive Industry
  • Flexible expansion joints
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About Glass Fibers

Fiberglass is the original fiber reinforcement of modern composites. Though the ancient Phoenicians, Egyptians and Greeks knew how to melt glass and stretch it into thin fibers, it wasn’t until the 1930s that the process evolved into commercial-scale manufacturing of continuous fibers, which would later be used as structural reinforcements. Patent applications filed between 1933 and 1937 by Games Slayter, John Thomas and Dale Kleist, employees of Owens-Illinois Glass Co. (Toledo, Ohio), record the key developments that step-changed the industry from producing discontinuous-fiber glass wool to making continuous glass filaments with diameters as small as 4 microns (4 millionths of a meter) and thousands of feet long. Ensuing breakthroughs made the process commercially viable and cost-competitive.

 

The last two patents in the series, entitled “Textile Material” and “Glass Fabric,” foreshadowed the future of glass fiber as a textile reinforcement. The patents were awarded in 1938, the same year that Owens-Illinois and Corning Glass Works (Corning, N.Y.) joined to form Owens-Corning Fiberglas Corp. (OCF).

 

The new company marketed its glass fiber under the trade name Fiberglas, which was the genesis of the common generic reference to fiberglass. It was not long before a number of other manufacturers entered the market and, through numerous process and product innovations, contributed to a worldwide structural composite reinforcements market of roughly 4 to 5 million tons per year.

 

Source: Composite World: http://www.compositesworld.com/articles/the-making-of-glass-fiber

Following are some Glass Fibers available in the market: 

AR-Glass * C-Glass * E-Glass * ECR-Glass * L-Glass * Quartz Glass * R-Glass * S1-Glass * S2-Glass * S3-Glass * Silica Glass * Other

Manufacturing Of Glass Fibers

The glass fiber process

Textile-grade glass fibers are made from silica (SiO2) sand, which melts at 1720°C/3128°F. SiO2 is also the basic element in quartz, a naturally occurring rock. Quartz, however, is crystalline (rigid, highly ordered atomic structure) and is 99 percent or more SiO2. If SiO2 is heated above 1200°C/2192°F then cooled ambiently, it crystallizes and becomes quartz.

Glass is produced by altering the temperature and cooldown rates. If pure SiO2 is heated to 1720°C/3128°F then cooled quickly, crystallization can be prevented and the process yields the amorphous or randomly ordered atomic structure we know as glass.

Although continuously refined and improved, today’s glass fiber manufacturers combine this high heat/quick cool strategy with other steps in a process that is basically the same as that developed in the 1930s, albeit on a much larger scale. This process can be broken down into five basic steps: batching, melting, fiberization, coating and drying/packaging.

Step 1: Batching

Although a viable commercial glass fiber can be made from silica alone, other ingredients are added to reduce the working temperature and impart other properties that are useful in specific applications.

For example, E-glass, originally aimed at electrical applications, with a composition including SiO2, AI2O3(aluminum oxide or alumina), CaO (calcium oxide or lime) and MgO (magnesium oxide or magnesia), was developed as a more alkali-resistant alternative to the original soda lime glass. Later, boron was added via B2O3 (boron oxide) to increase the difference between the temperatures at which the E-glass batch melted and at which it formed a crystalline structure to prevent clogging of the nozzles used in fiberization (Step 3, below).

S-glass fibers, developed for higher strength, are based on a SiO2-AI2O3-MgO formulation but contain higher percentages of SiO2 for applications in which tensile strength is the most important property.

In the initial stage of glass manufacture, therefore, these materials must be carefully weighed in exact quantities and thoroughly mixed (batched). Batching has become automated, using computerized weighing units and enclosed material transport systems. For example, in Owens Corning’s plant in Taloja, India, each ingredient is transported via pneumatic conveyors to its designated multistory storage bin (silo), which is capable of holding 70 to 260 ft³ (1.98 to 7.36m³) of material. Directly beneath each bin is an automated weighing and feeding system, which transfers the precise amount of each ingredient to a pneumatic blender in the batch house basement.

Step 2: Melting

From the batch house, another pneumatic conveyor sends the mixture to a high temperature (≈1400ºC/2552ºF) natural gas-fired furnace for melting.

Glass Melting

The furnace is typically divided into three sections, with channels that aid glass flow.

The first section receives the batch, where melting occurs and uniformity is increased, including removal of bubbles. The molten glass then flows into the refiner, where its temperature is reduced to 1370ºC/2500ºF. The final section is the forehearth, beneath which is located a series of four to seven bushings that, in the next step, are used to extrude the molten glass into fibers. Large furnaces have several channels, each with its own forehearth.
According to Scott Northrup, global business development director for AGY (Aiken, S.C.), furnace operation is being improved on several fronts.

The use of larger furnaces has increased throughput to between 30,000 and 40,000 metric tonnes (66.2 million lb to 88.2 million lb) per year.

One of the most important advances has been digital control technology. “Digital controls … measure and manage the precise temperature of the glass as it moves through the furnace as well as the gas … and oxygen flow rates.” They also maintain a smoother, steadier flow to the fiberization equipment, avoiding air bubbles or other interruptions that could cause discontinuities in fiber formation.

Control of oxygen flow rates are crucial because furnaces that use the latest technology burn nearly pure oxygen instead of air because it helps the natural gas fuel to burn cleaner and hotter, melting glass more efficiently. It also lowers operating costs by using less energy and reduces nitrogen oxide (NOx) emissions by 75 percent and carbon dioxide (CO2) emissions by 40 percent.

Because the furnace is a consumable — the process of melting and moving the glass wears away the refractory bricks that line the furnace interior — efforts are being made to increase the brick’s service life.

Glass fiber production is a continuous process, says AGY sales and marketing VP Drew Walker, “Once production begins, you don’t shut it down.”

Manufacturers say that a typical furnace averages 12 to 15 years between rebuilds, with seven years as a worst-case scenario. Walker explains that at up to $150 million for construction of a new manufacturing site and $10 million to $15 million for a new furnace or rebuild, extending furnace life translates directly into dollars.

The industry takes three main approaches to glass melting:

(1) indirect melt (also called marble remelt);

(2) direct melt using larger-scale furnaces (8,000 to 100,000 metric tonnes per year); and

(3) direct melt using smaller-scale furnaces (150 to 200 metric tonnes per year), which are also called paramelters.

For indirect marble remelt, molten glass is sheared and rolled into marbles roughly 0.62 inch (15 to 16 mm) in diameter, which are cooled, packaged and then transported to a fiber manufacturing facility where they are remelted for fiberization (see “Step 3”). The marbles facilitate visual inspection of the glass for impurities, resulting in a more consistent product.

The direct melt process transfers molten glass in the furnace directly to fiber-forming equipment. Because direct melting eliminates the intermediate steps and the cost of forming marbles, it has become the most widely used method.

Step 3: Fiberization

Glass fiber formation, or fiberization, involves a combination of extrusion and attenuation.

In extrusion, the molten glass passes out of the forehearth through a bushing made of an erosion-resistant platinum/rhodium alloy with very fine orifices, from 200 to as many as 8,000. Bushing plates are heated electronically, and their temperature is precisely controlled to maintain a constant glass viscosity. Water jets cool the filaments as they exit the bushing at roughly 1204ºC/2200ºF.

Attenuation is the process of mechanically drawing the extruded streams of molten glass into fibrous elements called filaments, with a diameter ranging from 4 μm to 34 μm (one-tenth the diameter of a human hair).

A high-speed winder catches the molten streams and, because it revolves at a circumferential speed of ~2 miles/~3 km per minute (much faster than the molten glass exits the bushings), tension is applied, drawing them into thin filaments.
The bushings are expensive, and their nozzle design is critical to fiberization. Nozzle diameter determines filament diameter, and the nozzle quantity equals the number of ends.

A 4,000-nozzle bushing may be used to produce a single roving product or the process can be configured to make four rovings with 1,000 ends each. The bushing also controls the fiber yield or yards of fiber per pound of glass.

(The metric unit, tex, measures fiber linear density; 1 tex = 1 g/km, and yield is the inverse, yd/lb.) A fiber with a yield of 1,800 yd/lb (275 tex) would have a smaller diameter than a 56 yd/lb (8,890 tex) fiber, and an 800-nozzle bushing produces a smaller yield than a 4,000-nozzle bushing. This helps to explain why Wisdom Dzotsi, Americas glass business manager for OCV Reinforcements (Toledo, Ohio, a combination of the reinforcements and fabrics businesses of Owens Corning and Saint-Gobain Vetrotex), views a 4,000-nozzle bushing as the sweet spot that has evolved for optimizing production flexibility.

In contrast, AGY uses 800-orifice bushings because, as Walker explains, “We are a smaller company whose glass yarn and specialty fiber business is based on finer filaments and smaller-run niche products.”

Bushing design is advancing. Kevin Richardson, market development director for PPG Industries (Pittsburgh, Pa.) notes, “There are emerging developments in bushing design that further enhance performance via tailored filament diameters and also contribute to total furnace throughputs, lowering cost.” AGY agrees, stating that the range of fiber diameter, or micronage, has become more varied as composite reinforcements have become more specialized. Although OCV sees 17 μm and 24 μm as the most popular diameters, its reinforcement products vary from 4 μm to 32 μm, while AGY’s products typically fall in the 4 μm to 9 μm range.

Walker notes that all fiberglass manufacturers want to produce as much glass fiber per hour as possible. Advances in winding have enabled producers to triple efficiency. Walker explains, “We process more packages at once now; 20 years ago we may have used two packages where now it is common to use six.” (See “Step 5.”)

Step 4: Coating

In the final stage, a chemical coating, or size, is applied. (Although the terms binder, size and sizing often are used interchangeably in the industry, size is the correct term for the coating applied, and sizing is the process used to apply it. See “Learn More,” at right.)
Size is typically added at 0.5 to 2.0 percent by weight and may include lubricants, binders and/or coupling agents. The lubricants help to protect the filaments from abrading and breaking as they are collected and wound into forming packages and, later, when they are processed by weavers or other converters into fabrics or other reinforcement forms.

Coupling agents cause the fiber to have an affinity for a particular resin chemistry, improving resin wetout and strengthening the adhesive bond at the fiber-matrix interface.

Some size chemistries are compatible only with polyester resin and some only with epoxy while others may be used with a variety of resins.

AGY, OCV and PPG agree that size chemistry is crucial to glass fiber performance, and each company considers its size chemistry to be proprietary.

PPG believes that in many composite applications, performance can be achieved via size chemistry as effectively as, if not more than, glass batch chemistry. For example, its 2026 size chemistry used with HYBON products for wind blades reportedly achieves an order of magnitude improvement in blade fatigue life by  improving fiber wet out and fiber adhesion to all resin types.

Step 5: Drying/packaging

Finally, the drawn, sized filaments are collected together into a bundle, forming a glass strand composed of 51 to 1,624 filaments. The strand is wound onto a drum into a forming package that resembles a spool of thread. The forming packages, still wet from water cooling and sizing, are then dried in an oven, and afterward they are ready to be palletized and shipped or further processed into chopped fiber, roving or yarn.

Roving is a collection of strands with little or no twist. An assembled roving, for example, made from 10 to 15 strands wound together into a multi-end roving package, requires additional handling and processing steps.

Yarn is made from one or more strands, which may be twisted to protect the integrity of the yarn during subsequent processing operations, such as weaving.

One process, many products

Although the basic glass fiber process has changed little since its commercialization 80 years ago, it has undergone many refinements. Two continuous threads run through fiberglass manufacturing’s history: the drive to increase production throughput and bring cost down and the desire to improve the performance properties of the finished product.

Manufacturers continue to push forward on both fronts in their pursuit of ever-newer applications for fiberglass-reinforced composite.

Source: Composite World: http://www.compositesworld.com/articles/the-making-of-glass-fiber

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Basalt Chopped Fibers

Basalt Chopped Fibers in general can be applied where E-Glass, sometimes S-Glass or Carbon Fibers can be used, as well.

.... more about the chopping process itself

As Basalt is more expensive than E-Glass, but cheaper than Carbon Fibers or S-Glass Fibers, it typically finds implementations, more suitable to its particular properties and fills an important gab when it comes to cost-performance ratios.

You can find a comparison to E-Glass, S-Glass or other materials by clicking here: Basic comparison to other fibers.

Knowing how Basalt compares to other fibers allow to precisely engineer an optimal solution, which could also be in form of a hybrid (combining Basalt with other Fibers made from Glass, Carbon, Kevlar, etc.)

 

An Example of an Engineered FRP. 

In Fiber Reinforcement Products (FRP) the engineer chooses the fiber, based on the desired outcome. E.g. if lighter weight requirements at identical strength to currently used fibers are required or if higher strengths are necessary while staying within the weight specifications.

There are other examples relevant to durability, corrosion resistances, break strength, chemical resistances, thermal applications, etc.

Our Team will be more than glad to assist or consult with design applications.

 

Applications: 

  • Leisure Industry (boats, surfboards, skateboards, etc)
  • Construction – reinforcements (asphalt, concrete)
  • Refractory – reinforcements (cermaic, microporous, other)
  • Processed into a Chopped Strand Mat
  • Processed into a Felt, Needled or acryclic bound like papers
  • Processed into a Phenolic Board
  • Thermal Insulation as filler material

Length: From 3mm (1/8 inch) up to 90mm (3.54 inch) are typical.

Filament diameter: From 13 micron up to 16 micron are standards

Chopped fibers can vary in looks when they are cut. Some distribute much more evenly others are staying together more like a strand; the choice depends on the application.